Two-parameter mixture model by Zhang and Luck (2008).

Usage

mixture2p(resp_error, ...)

Arguments

resp_error: The name of the variable in the provided dataset containing the response error. The response Error should code the response relative to the to-be-recalled target in radians. You can transform the response error in degrees to radian using the deg2rad function.
...: used internally for testing, ignore it

Value

An object of class bmmodel

Details

Domain: Visual working memory
Task: Continuous reproduction
Name: Two-parameter mixture model by Zhang and Luck (2008).
Citation:
- Zhang, W., & Luck, S. J. (2008). Discrete fixed-resolution representations in visual working memory. Nature, 453(7192), 233-235
Requirements:
- The response vairable should be in radians and represent the angular error relative to the target
Parameters:
- mu1: Location parameter of the von Mises distribution for memory responses (in radians). Fixed internally to 0 by default.
- kappa: Concentration parameter of the von Mises distribution
- thetat: Mixture weight for target responses
Fixed parameters:
- mu1 = 0
- mu2 = 0
- kappa2 = -100
Default parameter links:
- mu1 = tan_half; kappa = log; thetat = identity
Default priors:
- mu1:
  - main: student_t(1, 0, 1)
- kappa:
  - main: normal(2, 1)
  - effects: normal(0, 1)
- thetat:
  - main: logistic(0, 1)

Examples

if (FALSE) { # isTRUE(Sys.getenv("BMM_EXAMPLES"))
# generate artificial data
dat <- data.frame(y = rmixture2p(n=2000))

# define formula
ff <- bmmformula(kappa ~ 1, thetat ~ 1)

model <- mixture2p(resp_error = "y")

# fit the model
fit <- bmm(formula = ff,
           data = dat,
           model = model,
           cores = 4,
           iter = 500,
           backend = 'cmdstanr')
}